To the Editor: The study by Dr Mehta and colleagues1 supports the prognostic importance of ventricular tachycardia or ventricular fibrillation (VT/VF) as an independent predictor of early mortality in patients with ST-segment elevation myocardial infarction (STEMI) treated with percutaneous coronary intervention. Although the authors warned about the limitations of the study, we believe that not considering left ventricular ejection fraction (LVEF) among the predictors of mortality in the multivariable models represents a serious limitation that hinders the interpretation of these data. Left ventricular ejection fraction is a strong predictor of mortality in patients with STEMI,2 and assessing the prognostic value of other covariates without correcting for LVEF may lead to unreliable results. Since there is no adjustment for LVEF, the results of this study may lead to the conclusion that patients who have a preserved LVEF and experience VT/VF, mostly during catheterization, have a 3-fold increase of mortality compared with patients who have a poor LVEF but did not have VT/VF.
The authors did not consider LVEF because it was available in the database in only 45% of patients. They noted that when they ran the model including only those patients who had LVEF measured, it was not independently associated with VT/VF. However, they did not test whether LVEF was an independent predictor of mortality and how the other covariates could have changed if LVEF had been considered.
Moreover, LVEF may be the key element to reconcile discrepancies with other studies that did not find any relation between VT/VF and mortality.3 The authors mentioned the Primary Angioplasty in Myocardial Infarction (PAMI) study3 and suggested that the absence of relation between VT/VF and mortality could have been due to enrollment of low-risk patients in that study. This observation strengthens our point of view because in PAMI most patients had preserved LVEF; in such patients VT/VF may not have a prognostic effect.
These considerations may challenge the perspective provided by the study by Mehta et al, which suggested that the occurrence of every VT/VF should be considered as a marker of increased risk of mortality and should prompt further investigations to explore the relative importance of LVEF and VT/VF in determining the risk of mortality. We encourage the authors to provide the data on the risk of mortality in those patients for whom LVEF was available and to better characterize the possible interaction between VT/VF and LVEF with respect to mortality.
Financial Disclosures: None reported.
Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
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